For many years brake control valve devices used on railway vehicles have comprised both a service valve device and an emergency valve device each of which has a main slide valve that has passageways and cavities therein. This main slide valve has a flat bottom slidably mounted on a ported flat slide valve seat formed on and within a casing member. A graduating slide valve that has a flat bottom is slidable with respect to a ported flat valve seat provided therefor on the top of the main slide valve.
The maintenance of slide valves is expensive in that mechanics having considerable skill are required to lap and fit a slide valve to its seat. On the other hand, most any ordinary workman is able to remove worn O-ring seals from a spool-type valve and replace them with new seals.
According to the present invention, a railway vehicle brake control valve device is provided with a service valve portion, the valve body of which has therein a plurality of passageways opening at their respective opposite ends at the wall surface of bores in this body, each bore having slidably mounted therein a spool-type valve the periphery of which is provided with one or more elongated annular grooves and, adjacent each end of each elongated annular groove, an annular groove in which is disposed an O-ring seal that forms a fluid tight seal with the wall surface of the corresponding bore. A pair of large diameter bores has large capacity spool-type brake cylinder application and release piston valves slidably mounted therein to control the flow of fluid under pressure to and from a brake cylinder while another spool-type valve of smaller diameter slidably mounted in a third bore and operated by a movable abutment connected thereto controls the supply and release of the fluid under pressure for operating the two large capacity spool-type piston valves, the charging of an auxiliary and an emergency reservoir from a train brake pipe and the release of fluid under pressure from a train brake pipe to a quick service volume chamber. The service portion of this brake control valve device also includes diaphragm-operated limiting and accelerated service release valves for respectively controlling flow of fluid under pressure from the quick service volume chamber to the brake cylinder and from the emergency reservoir to the train brake pipe when effecting a brake release subsequent to a service brake application.